(1) Technical Field
The present invention relates to an image forming apparatus having a mechanism that homogeneously charges a photoconductor by applying an AC component and a DC component thereto according to a contact or proximity charging method on a charge-by-discharge basis, and more specifically to a technique of measuring the film thickness of a photoconductor.
(2) Related Art
Various components (such as a charging roller, a development brush, a transfer roller, a cleaning brush, and a cleaning blade) are provided on a surface of a photoconductor provided in an image forming apparatus in physical contact with the surface. A photosensitive layer formed on the surface of the photoconductor has its surface gradually worn by repetitive physical contact with such components for each step of image forming processing. Frictional force by the cleaning brush and the cleaning blade is particularly significant and plays a large part in the wearing away of the photosensitive layer.
When the photosensitive layer has its thickness reduced to a predetermined degree or more by the wear, the photosensitivity may significantly be reduced or the charge characteristic degrades, the surface cannot be charged homogeneously to a predetermined potential, and a clear image can no longer be formed. The thickness of the photosensitive layer of the photoconductor should be measured, and the useful life of the photoconductor should be notified.